Susan Brownmiller (born February 15, 1935) is an American feminist, journalist, author, and activist. She is best known for her pioneering work on the politics of rape in her 1975 book Men, Women, and Rape Brownmiller argues that rape had been hitherto defined by men rather than women; and that men use, and all men benefit from the use of, rape as a means of perpetuating male dominance by keeping all women in a state of fear. The book received criticism from Angela Davis, who thought Brownmiller disregarded the part that black women played in the anti-lynching movement and that Brownmiller's discussion of rape and race became an "unthinking partnership which borders on racism". In 1995 The New York Public Library selected Against Our Will as one of 100 most important books of the Twentieth Century.

Brownmiller also participated in civil rights activism, joining CORE and SNCC during the sit-in movement and volunteering for Freedom Summer in 1964, where she worked on voter registration in Meridian, Mississippi. Returning to New York, she began writing for The Village Voice and became a network TV newswriter at the American Broadcasting Company, a job she held until 1968. She first became involved in the Women's Liberation Movement in New York City in 1968, by joining a consciousness-raising group in the newly-formed New York Radical Women organization. Brownmiller went on to co-ordinate a sit-in against Ladies' Home Journal in 1970, began work on Against Our Will after a New York Radical Feminists speak-out on rape in 1971, and co-founded Women Against Pornography in 1979. She continues to write and speak on feminist issues, including a recent memoir and history of Second Wave radical feminism. In Our Time: Memoir of a Revolution (1999).

Against Our Will was one of a number of feminist bestsellers of the early 1970s which took extremely negative positions on the previous history of the human race. Others included Jill Johnston's Lesbian Nation (1973), which called heterosexual females 'traitors'; Kate Millett's Sexual Politics (1970), which defined heterosexual sex as a power struggle; Kathrin Perutz's Marriage is Hell (1972); and Ellen Peck's The Baby Trap (1971), which argued that babies block liberation.

Against Our Will received a lot of media attention when it was published, much of it critical. Amanda Heller of The Atlantic Monthly noted the tendency towards "a kind of feminist pornography that overwhelms the book's more thoughtful passages." M. J. Sobran ironized in the National Review, "What she is engaged in, really, is not scholarship but henpecking...that conscious process of intimidation by which all women keep all men in terror."

Brownmiller was born in Brooklyn to Mae and Samuel Warhaftig, a lower-middle-class Jewish couple. Her father was a sales clerk in Macy's department store, and her mother was a secretary in the Empire State Building.

As a child she attended the Ocean Avenue synagogue, and she was sent to a Hebrew School there for two afternoons a week to learn Hebrew and Jewish history. She would later comment, "It all got sort of mishmashed in my brain except for one thread: a helluva lot of people over the centuries seemed to want to harm the Jewish people. ... I can argue that my chosen path - to fight against physical harm, specifically the terror of violence against women - had its origins in what I had learned in Hebrew School about the pogroms and the Holocaust."

She had "a stormy adolescence", attending Cornell University for two years (1952 to 1954) on scholarships, but not graduating. She later studied acting in New York City. While training as an actor, she took the stage name Brownmiller, legally changing her name in 1961.She appeared in two off-Broadway productions.

Brownmiller's interest in journalism began with a position at a "confession magazine". She went on to work as an assistant to the managing editor at Coronet magazine (1959—1960), as an editor of the Albany Report (1961—1962), and as a national affairs researcher at Newsweek (1963—1964). In the mid-1960s, Brownmiller continued her career in journalism with positions as a reporter for NBC-TV in Philadelphia (1965), staff writer for the Village Voice (1965), and as network newswriter for ABC-TV in New York City (1966—1968). Beginning in 1968, she worked as a freelance writer; her book reviews, essays, and articles appeared regularly in publications including the New York Times , Newsday , the New York Daily News , Vogue , and the Nation.

She describes herself as "a single woman", even though "I was always a great believer in romance and partnership." "I would like to be in close association with a man whose work I respect," she told an interviewer, attributing her continued celibacy to the fact that she was "not willing to compromise."

Her papers have been archived at Harvard, in the Arthur and Elizabeth Schlesinger Library on the History of Women in America.